From Stellar Wind to Sun?

A new theory suggests that a "wind" of ionized particles from a star may have spurred a change in the distribution of mass inside of our sun's nebula, causing some hydrogen to clump together and form our sun. The solar wind is something that is very familiar to our part of the solar system. It is a contiuation of the sun's corona which extends all the way past Pluto to the heliopause, where it meets the interstellar wind, which finally ends any significant effects of the solar wind. It is composed of a plasma. A plasma is a gaseous state consisting of positive and negative ions and which is very liable to electrical and magnetic interactions because of its possibilities for conductivity.
When the sun was a T-Tauri star (a baby which didn't fuse Hydrogen yet) it emitted 1000 times more solar wind than it does now, and even now it is still emitting enough to help cause auroras, geomagnetic storms, communication problems on satelites and, every once in a while a really really energetic particle like the "Oh My God" particle, which was a proton with as much energy as a 60 mpH baseball!
It was thought that the sun formed from its nebula because of a shockwave from a nearby supernova which changed the density of the nebula and allowed some the of the hydrogen to clump together. Now, though, scientists are proposing a less explosive culprit, stellar wind.

Axions: Fact or Fiction?

Axions are theoretical particles that, if verified, could help explain what dark matter is made of.

Why do we need Axions?
In 1977, Roberto Peccei and Helen Quinn proposed an elegant solution to the strong CP problem which required a new particle, which they called an axion. It's named after a popular detergent of the time because they had "cleaned up" the problem.

CP Problem? What are you talking about?
CP stands for charge conjugation(C) and parity(P). They are symmetries in Particle Physics. In other words, we somehow change the conditions of an experiment in order to check whether a certain symmetry can be maintained under some circumstances. Charge conjugation is a symmetry involving particle/anti-particle trasitions. Think of parity as a reflection symmetry. When put together they make CP symmetry. It was established in the 50's that Parity violation (reflection) was broken in weak nuclear interactions. This was exciting as this symmetry wasn't broken in any of the other forces. So Physicists combined Parity with Charge Conjugation and thought that together they wouldn't be broken. Wrong. Even together weak interactions still violated the symmetry. So CP Violation was discovered in the weak force.

What about the Strong CP Problem?
Well, when the experimentation was carried over to the strong nuclear force, Physicists were puzzled that CP symmetry did not appear to be violated much, if at all. One parameter in the theory of Quantum Chromodynamics [QCD] (the theory of the strong force) had to adjusted very precisely in order to agree with experimental data. The Strong CP problem is basically asking why the Strong Force doesn't suffer from CP Violation like the Weak force does.

What about Axions?
Like I was saying there is a very precise parameter in QCD which is very close to zero but not quite there in order to compensate for the lack of CP Violation. Peccei and Quinn suggested the elegant idea of making this parameter into a new field, and where there is a field there must be a new particle of that field. In this case this particle would be called an axion. This may sound contrived but it is legal. Peccei and Quinn suggested a new symmetry (Peccei-Quinn symmetry) that would be spontaneously broken and produce this new particle, allowing the parameter from QCD to drop to zero, which seems more natural.

How do we detect Axions?
It is theorized that Photons, when exposed the magnetic fields, will spontaneously change into Axions. One novel way to detect them that has come up this week was discussed in depth here. Basically, we will wait until a giant quasar goes behind our sun and then we will wait to see whether we will still be able to detect anything from the quasar even though the sun is in the way. The idea is that high energy photons from the quasar will change into axions from the suns magnetic field and then change back and come to us.

So what if we find them?
If we find them then we may have an answer to what dark matter is. They are theorized to be very light (maybe less an meV) but they are also theorized to have been created in huge numbers during the big bang, when they would have lost all of their kinetic energy and become Bose-Einstein Condensates (substances that can't lose any more energy and can't degenerate into anything smaller).

Beautiful Picture of Saturn with Sun Behind

Every once in a while an image comes from one of our telescopes in space that just blows the mind. Here is one I particularly liked. This is an image taken by Cassini of Saturn with the sun directly behind it.


Saturn with the Sun behind it and the Earth as one of the little specks of light on the left

Zooming in to the original image we can see Earth as one of the bright dots near the rings.


Earth

SN 2006gy and Pair Instability Supernovae

Like explosions? Well, supernovae are the biggest ones in the whole universe. Some can outshine their entire host galaxy and last week, astronomers observed their biggest one yet, called SN 2006gy.


SN 2006gy is the bright spot on the right. It's entire host galaxy is the darkish green blur one the left.

It came from a star more than 150 times the mass of our sun. It is an example of a very rare type of supernova called a pair instability supernova. In these kinds of supernova a high energy photon (gamma ray) coming from the fusion areas within the star spontaneously forms a particle anti-particle pair and is either deflected in a different direction when the two particles collide or not recreated at all, thus reducing the light pressure on the surface of the star. This allows gravitational forces to win out on the surface of the star, causing it to contract.


An illustration of the mechanisms involved in pair instability supernova.

When the gammas produce pairs of particles, they travel less on average, thus heating the innards of the star, thus causing it to produce more gammas. The process goes on until the core of the star explodes with more force than the gravity that holds the star together. This can only occur in stars with more than 130 times the mass of the sun. In lesser massed stars, the process may even out and lead to a semi-stable, pulsating star. In the big stars though, it can produce what we saw with SN 2006gy, namely, an enormous bang:

Gliese 581c Video

Just a good video I found giving a bit more info and some nice pictures about Gliese.

More Planet News

This week the interesting planet news continues. After last week’s massive news about Gliese 581 C, this week’s news seems pretty uneventful but it is still important in understanding the possibilities for extra solar planets. Many people may be left with a human-friendly impression of exoplanets after Gliese but the news about the temperatures on a couple of hot Jupiter planets should quickly bring those people back to the reality that most exoplanets are about as non human-friendly as is possible.

Firstly, the mapping of temperature distribution on HD 189733b shows that this planet ranges between 1200 degrees Fahrenheit on the hemisphere facing away from the star to 1900 on the hemisphere facing the star. The planet is tidally locked to its star, an inconspicuous yellow dwarf like our own star. The fact that the temperatures are not more radically different on the different sides of the planet suggest that there are some pretty ridiculous winds involved to spread the heat around, winds that scientists say could be as fast as 6,000 mi/hr. This is one of the rare times that astronomers have been able to map the full surface of an exoplanet according to temperature variations along its surface. Another interesting thing about the planet is that it goes around its star in only two Earth days and therefore is a close transiting planet. In fact, the HD 189733 system is one of our best resources for learning about close transiting planets like this.


Image of the temperature on the surface of HD 189733b courtesy of NASA

The second planet I want to talk about, HD 149026b, is even more disturbingly anti-humanity. It is one of the hottest planets ever observed with temperatures over 3700 degrees Fahrenheit! It is so hot that it is hotter than some low mass stars. This planet, unlike the other one, probably doesn’t have its heat spread around both sides. It is also pretty small for this type of planet and extremely dense with very intense gravity. Astronomers are proposing that it may be a very dark world because it is so hot. Most of the light and energy from the star is obviously being sucked up into the planet, without much being reflected off of it for us to see. All in all, this chunk of coal is one of the weirdest exoplanets discovered yet.

An artist's conception of HD149026b, the hottest planet ever seen. Courtesy of NASA.

Both discoveries were made by measuring changes in infrared radiation as these planets went behind their stars. The observations were performed with the Spitzer Space Telescope.

First Earth-Like Exoplanet Found!!!

Artist's Impression of Gliese 581 System

This has to be one of the most exciting things I've heard in years. Astronomers in Chile have found the first ever Earth-Like Exoplanet! This is the first time we have evidence for our hopes that our Earth is not the only habitable planet.
The planet, Gliese 581 C, goes around an M dwarf (see diagram in previous post for classification clarification) star at a very tight radius with a year of only 13 Earth days. It is 50% bigger than the Earth and is five times heavier. The system is 20 light years away.


Gliese 581, the M dwarf around which the planet orbits

This is exciting because it is the first planet we have ever seen (besides Earth) that can support liquid water. The temperatures are a bit higher than here on Earth but not too different (between 0-40 degrees Celsius). This is assuming an Earth-like atmosphere, which may not be the case. The proposition is that this world is either a rocky planet or one that is completely dominated by water and oceans.
This is exactly the kind of planet SETI expects to find intelligent life on. After two sweeps a couple of years ago they didn't find anything but I'm sure they will be looking again, this time much more carefully. I'll be stepping up my SETI@Home dedication in the mean time. Even if it's not occupied, then it may be our home far in the future, when we've finished pillaging the Earth.

Solar System Podcast

Podcast Stream:



Some of the stuff I mentioned:


Herzprung-Russell Diagram


Diagram of the outer extent of the solar wind

For a scale model of the solar system check this out.

Music this episode was We are Electric by the Flying Steps.

Gagarin and Special Relativity Podcast

Podcast Stream:



First thing I have for you is a real treat. This is Feynman's Lecture on Special Relativity. Listen to this for a deeper understanding of the subject.



A couple of corrections and stuff:

-Gagarin died at 34, not in his late 30's or early 40's as I suggested.
-The Speed of Light is 186,000 mi/s, as I tentatively proposed.
-Every time I said the word "moving" without the word "relative" right after it, it should have killed your soul a little bit. Sorry about that. You fill in the blanks with what makes sense and heal your soul. :)

Demystifying Special Relativity, Part 2

OK, so we know what the theory of Special Relativity says. Now I want to examine some of the consequences that arise. Please understand that Special Relativity and it's effects are not things that we normally feel on a day to day basis. This is because neither we nor anything that we (unless you're in some specialized profession) care about moves anywhere near the speed of light relative to anything that matters to us. This is what makes the ideas of Special Relativity seem so crazy sometimes. We need to stretch our common sense notions of space and time, in order to really get a grasp of the theory and its effects.

Time Dilation

Imagine a clock like the one shown below. It has a light source on the bottom, a mirror on top, and a detector on the bottom to detect the signal when the light comes back down. So the time for it to go up and down is the twice the height of the light clock divided by the speed of light, c.
Now imagine that the light clock is moving relative to you. You would see the light follow a triangular path, like that shown in the second picture in the series below.



Basic trigonometry and the Pythagorean theorem will inform you that the distance from the detector to the mirror and back in your reference frame is greater than that in the proper frame of the clock. Proper is just a word that means in the rest frame. So now we know that the distance traveled for the light to get back to the detector in a non-proper frame of the clock is larger than in the proper frame of the clock. We also know, from the laws of electromagnetism, that light travels at speed c, always. So, we have the same speed and a larger distance. Because time elapsed is inversely proportional to velocity and directly proportional to distance, as distance increases, time elapsed also increases.

The time elapsed in a reference frame moving with respect to an observer is longer than that elapsed in the proper frame of the observer. When something moves and an observer looks at the moving thing, he sees time go by slower in the moving thing.

Note: Everything seems normal to the moving guy. In the guy's proper frame everything is just like it would be if he was in any other uniform state of motion.
Note: The Light Clock used above is just an example. Time dilation is not some unique effect of the light clock, nor is it just an effect of clocks in general. Time dilation is a property of space-time, which is the framework of our universe.

In the next entry I'll discuss length(Lorentz) contraction and start discussing what space-time is.

Demystifying Special Relativity, Part 1

This is the first part of what will be a multi-part series on Einstein's Special Relativity, which is probably the single most important law for understanding modern Physics and one that is not as complicated as some people think. I'll try to avoid the math here; after all, this is a Physics blog, and Physics is primarily about concepts.
I'm putting a few entries on relativity here because I feel like you need to understand it in order to really understand most of the news entries about modern Physics and Astronomy I will be posting. I know you can read all this information off of Wikipedia and other sources, but I'll try to make it more digestible for non-scientists and you can leave comments if you have any questions.

Galileo: The first principle of Relativity


Galileo's sketch of Jupiter and some of it's moons orbiting it, showing that not every celestial body goes directly around the Earth

Galileo was the first person to propose a theory of relativity. His theory of relativity (sometimes called Galilean Invariance) basically states the following

Newton's laws hold in all inertial reference frames

Let's look at this carefully. Newton's laws are the basic laws of mechanics and kinematics. I'm not going to go in depth into what these laws are but you check them out in more detail here.
An inertial reference frame is one that is moving at a constant velocity. That is, it has a constant speed and a constant direction.
An example of what Galileo's Principle says is that if you are playing table tennis on an inertial train, the game will have to follow the same rules of Physics as a table tennis game played on the ground that the train is moving relative to. This idea of relative motion is really important in both Galilean and Special Relativity. This is because relativity implies that there is no absolute state of motion. If you are on the train traveling at speed v relative to the ground, are you the one who is moving or is the person on the ground you see moving past you at speed v? From your perspective, the guy on the ground is moving at speed v away from you. That's your frame of reference in this situation. From the ground the guy think you are moving at speed v. So, the important point is that there is no absolute motion.
So that is the original principal of relativity. That's it.

Einstein's Great Idea
So what was Einstein's ingenious idea that makes most people think that this theory is so hard? What is the incomprehensible, fantastically amazing, conjecture that Einstein made.

Galilean Relativity said that the laws of motion were the same for all inertial reference frames. Einstein's Special Relativity says that the laws of motion and all other laws of Physics were the same in all reference frames.

That's it. Most of the weird consequences that pop out of Special Relativity come from one law of Electromagnetism. That law is:

Electromagnetic Radiation (including visible light) travels at speed c=299,792,458 m/s=670,616,629.384 miles per hour

Scale model of light traveling from Earth to Moon; the time for light to get there is correct.

The law of special relativity is not so much about things being relative as it is about one thing being constant (the speed of electromagnetic radiation). In order to keep this quantity constant, the static character of space and time has to be given up. In other words, space and time have to change so that the speed of light doesn't change. I will explain how they do this in the next post.

I think that's enough for today. Think about that and I'll continue this ASAP.

Voyager: Our Bottle in the Cosmic Ocean

"...the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet." Carl Sagan on the Voyager 1

I mentioned in the podcast yesterday the Voyager spacecraft, which was sent into space in 1977 and which is now further out than the orbit of Pluto. I know I promised real hard science but I feel like the story of this craft is really inspiring and thought provoking.

Voyager 1

The Voyager spacecraft carried a golden record containing various images and sounds from the Earth and from our civilization. This "Golden Record" is really amazing and deserves some attention. Most of all, the idea of representing humanity as one united civilization is one that gives me a lot of hope for the future.

The Golden Record, which was onboard Voyager 1

What's all the gibberish on the front of the record?

I'll let the official NASA documentation explain all this. It's really fascinating to think about how to communicate with beings that may be completely different from us. Some really smart people worked up a way to try to give the beings instructions for playing the record.



How do we represent ourselves to these beings?

I feel like this is the really interesting question that this record and the Voyager mission brings to light. In the midst of the Cold War, all of humanity took it upon themselves to present a united front to any being that will find this record in the distant future. We weren't trying to represent America, or the USSR, or any specific people or country as special. For the first time in the history of humanity, we had to think about ourselves as one, united species.

This is a message on the record from the Secretary General of the United Nations at the time, Kurt Waldheim:

"As the Secretary General of the United Nations, an organizations of the 147 member states who represent almost all of the human inhabitants of the planet earth. I send greetings on behalf of the people of our planet. We step out of our solar system into the universe seeking only peace and friendship, to teach if we are called upon, to be taught if we are fortunate. We know full well that our planet and all its inhabitants are but a small part of the immense universe that surrounds us and it is with humility and hope that we take this step."

What a beautiful message! I love the idea of people being able to think of themselves as human inhabitants of the planet Earth, instead of just Germans, Russians, Americans, etc.

Here is a message from US President at the time Jimmy Carter:

"We cast this message into the cosmos . . . Of the 200 billion stars in the Milky Way galaxy, some - - perhaps many - - may have inhabited planet and space faring civilizations. If one such civilization intercepts Voyager and can understand these recorded contents, here is our message: We are trying to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of Galactic Civilizations. This record represents our hope and our determination and our goodwill in a vast and awesome universe."

Community of Galactic Civilizations? I don't think I need to say how touching these messages are.

There were also visual and audio representations of human civilization on the record. I'll leave you with some of my favorites and a link where you can see all of the rest of them. As you look at these pictures, be proud to think of yourself not as a German, Russian, American, etc., but as a human being.


Diagram of Vertebrate Evolution






UN Building at Night



See the rest of the images and hear how we want to represent our civilization and our world through audio here.

Fermi Paradox: Where is Everybody? Podcast

The first Podcast is out. It's about the Fermi paradox and possible resolutions to it. I realize some of my more scientifically rigorous subscribers may not be very happy with the science fiction slant in this podcast, but I wanted to start the podcasts with something really fascinating to think about. We'll get to some rock solid science soon enough, I promise.

Here are some links from the show:


This is the "Golden Record" sent with the Voyager spacecraft on a journey out of our solar system and, hopefully, into the arms of eagerly waiting alien civilizations. Click on the picture for a link to the Wikipedia entry. Carl Sagan co-wrote a book about the record and all the stuff on it called "Murmurs of the Earth"

Solve the Drake Equation. I got 200 when I did it.

SETI@Home; sign up, help find E.T.

End music was Bubble - Deadender

SETI; worth our taxes?

Is SETI (The Search for Extraterrestrial Intelligence) worth our taxes? I think their mission is definitely worthwhile. Imagine the impact it would have on the world if we tuned in to some faraway system and heard


Meesa Jar Jar Binks

OK, bad example. But seriously, it's very difficult to think of things on the cosmic scale with our non-cosmic sized minds. The chances of finding intelligent life on any particular planet are absolutely minuscule, pretty much zero. However, there are so many planets and systems to examine, that it just might be possible to detect something if we look in enough places.

There may not be a pay off in the next five or ten years, but we may find some signs of civilization in the next century. Even then, the impact will be more philosophical than practical. Communicating across the cosmos with the laws of Physics that we know of today is very inefficient and useless.

I won't go into all the gory details of how SETI tries to detect civilizations, but you can read all about it (Wikify!). Basically, they scan the skies for radio signals, like the ones we emit from TV's, radios, phones, etc. How do they know the aliens don't communicate using something we don't know how to use yet (elementary particles, qubits, donuts)


Incentive for alien invasion: donut shortages?

In conclusion, I think it's pretty arrogant of us to assume we could detect an advanced civilization but I'd give up one penny per paycheck to support any efforts.

Also, there is a really wacko philosophical idea that's pretty fun to think about and that I think everyone should check out that pertains to E.T. and our relations to him. It's called the Zoo Hypothesis (Wikify!) and I think I will dedicate a full post to it and other explanations for the Fermi Paradox in the near future.

And, finally, I leave you with this gem:

Pandora, Apples, and the Universe

I've recently found Pandora, the fantastic music discovery tool. If you haven't seen it yet, then I really recommend it. It has the best selection of music that I've ever seen. If you want new music: Go check it out . Two new bands I recommend are Bubble and Thirsty Merc.

The new version of iTunes is making me happy. The old version used to crash automatically after any uploads to my iPod which almost gave me enough incentive to use Rockbox. Rockbox seemed like it would take a lot of setting up though, so I decided to stick it out with iTunes, and the new version is workable.

Also, I found a new interesting podcast about Neurology, hosted by some Aussie woman. It's called All in the Mind.


Hubble is coming down. It's been up there since 1990 and has completely changed the view of the universe of those who have been paying attention for the last few years. Here is a nice video about the UDF (Ultra Deep Field), one of the most distant glances we have ever taken into our universe.